1. Field of the Invention
The invention relates to a geared pump for conveying fluids lacking or having insufficient lubricating ability, the pump including at least one connection for suction of the fluids and at least one connection for expulsion of the fluids, ducts and interstices joining the connection for the suction of the fluids and the connection for the expulsion of the fluids, and a conveying device for the fluids that is disposed in one of the interstices and includes an operating chamber in which two gearwheels rotate, the gearwheels mesh with each other while generating conveying spaces and reducing the conveying spaces again down to a minimum value, at least one duct on the suction side opens into the suction side of the operating chamber and at least one duct expels the fluids issuing from the pressure side of the operating chamber, and the meshing gearwheels are formed of a material from the group consisting of nonferrous metal, steel, special steel, industrial ceramics, metals and metal alloys produced by powder metallurgy, thermosetting and thermoplastic synthetic materials, thermosetting and thermoplastic synthetic materials containing fillers and synthetically produced carbon.
Geared pumps with an internal gear tooth system and those with an external gear tooth system are used in technology to a considerable extent for hydraulic power transmission in the pressure range of about 10 to 250 bar. They are used in the pressure range of about 2 to 10 bar for pure conveying tasks for the conveying of lubricating fluids such as oils of all kinds or of diesel fuel. When conveying fluids which lubricate badly or not at all, for example water, low-boiling hydrocarbons, in particular gasoline or kerosene, or liquids formed of solutions or mixtures, with the use of geared pumps, problems occur even after a short time at low output-side fluid pressures of about 2 to 10 bar. The friction becomes too high and the pumps fail due to erosion and/or corrosion. Problems of that kind also lead to the failure of the pumps in operating fields where temporary dry operation or periodically interrupted lubricating films have to be used.